Debris Disks

Unifying Debris Disk Morphology

Debris disks are the leftovers of planet formation; they are disks (primarily) of solids: dust and rocks. One way to study the overall shape and the inner structure of these disks is to image them in the optical and the infrared. Images of debris disks reveal a wide variety of shapes. Some of the non-axisymmetric features (e.g., HD 15115 showcases an extreme radial asymmetry, like a needle) are often considered as signs of a planet on an eccentric orbit, yet to be detected. We expect an eccentric planet to shape an eccentric disk but is a single planet enough to describe the myriad morphologies found in observations?

Using a "minimum model" of debris disks---a narrow ring of boulders secularly forced by a planet, colliding to produce dust grains perturbed by stellar radiation pressure---we show in Lee & Chiang 2016 that an eccentric disk sculpted by a single planet on an eccentric orbit can "change its shape" as we change our viewing angle:

Top: synthetic scattered light image of a disk sculpted by a planet with eccentricity = 0.7

Varying the observing angle, planet eccentricity, and the distribution of dust grain launch sites, we identify 6 types of disk morphology:

See also my poster from Exoplanets I meeting in Davos 2016 for a graphical summary.